Various modifications were made to reduce escaping gasoline vapours; they include redesigned bowl vents, low bowl capacity, heat shields, and better insulation between intake manifolds and carburettors. This should eliminate the release of fuel tank vapors into the atmosphere through a carbon canister storage which holds in its storage activated carbon device which collects the vapors produced from the engine induction system every time the engine is off. When operating some of the stored fuel vapors are expelled by the intake air and burnt normally. The 231 V6 engine introduced in 1981 has an electronically controlled purge function through a solenoid connected to the Electronic Control Module (ECM) managing vacuum to the purge valve depending on the system mode. Earlier carbon canisters are generally open that sucks in air from the bottom of the canister but some of the newer models have got the closed canister system that draws its air from the air cleaner. Service entails from time to time replacing the canister filter if any, or any replacement fuel tank cap to its original type. For canister removal, hoses are disconnected, retainer screws are turned back, and the canister is lifted off the car; if the car is equipped with A/C, additional exposure buttons are loosened as well. The canister is then labeled and disconnected for use; installation, on the other hand, is done in the following order. To replace the filter, the vapor canister is taken off, then the filter is pulled out from the bottom and a replace it with a new one then the canister is replaced.